1.) Someone with an unnatural compulstion to wear spikes and all things metal on all parts of their body. Often associated with maschisocism. Very sexy on girls.
2.) Someone who spikes people's drinks at a party, I.E: Adding drugs/alcohol to them for fun or profit.
3.) Madman (my buddy, not the admin) on a really fucking bad day.

1.) The spiker drifted gracefully into the room, and the preppy girls cringed at the safety pins driven through his arms and thumbs.
2.)
A.)Tom is such a spiker. We want him at the party?
B.)Only for the girlfolk.
3.)
A.)Holy shit, madman went spiker today.
b.)Oh shit, where do we hide now?

A "Skunktail"(suppository pill filled with kief) laced with PCP, LSD, Roofalin, and over-the-counter laxatives. Rendering the victim helpless, paranoid, disassociated, and covered in feces. Spikers are used to achieve a drug facilitated sexual assault. Spiker became a household name when several Bathhouse visitors came forward in the mid 90's of being sexually assaulted.

It's also been known as "spiking" and/or "getting spiked".

Guy 1: Did you hear about John?
Guy 2: Yeah, someone gave him a Spiker and at The White Dove. He thought it was a Skunktail. Get this, he lost all his money, his ID, and most of his clothes.
Guy 1: Is he still shitting?
Guy 2: Hasn't stopped.

A "spiker" is a rogue pubic hair that takes on the persona of an extremely hard piece of cotton (or even fishing twine) that has set up house in the front part of your undies. And usually makes an appearance when one is in a public place. Creating an irresistible urge to scratch your groin.

John got a spiker while at the supermarker. Drove him crazy trying to scratch it without being seen.